Asphalt-surfaced roadways are built to facilitate vehicular travel. Depending upon usage density, base conditions, temperature variation, moisture levels, and/or physical age, the surfaces of the roadways eventually become misshapen and unable to support wheel loads. In order to rehabilitate the roadways for continued vehicular use, spent asphalt is removed in preparation for resurfacing.
Cold planers, sometimes also called road mills or scarifiers, are used to break up and remove layers of an asphalt roadway. A cold planer typically includes a frame propelled by tracked or wheeled drive units. The frame supports an engine, an operator's station, a milling drum, and conveyors. The milling drum, fitted with cutting tools, is rotated through a suitable interface with the engine to break up the surface of the roadway. The broken up roadway material is deposited by the milling drum onto the conveyors, which transfer the broken up material into haul vehicles for removal from the worksite. As haul vehicles are filled, they are replaced with empty haul vehicles. The filled trucks transport the broken up material to a different location to be reused as aggregate in new asphalt or otherwise recycled. This transport process repeats until the milling process is finished.
Operators may wish to fill each truck to a maximum legal or desired capacity before replacing it with an empty truck in order to reduce waste, improve efficiency, and comply with applicable laws. To help calculate how much material has been milled and loaded into a truck, manufacturers have equipped conveyors with material measurement systems. Known measurement systems typically sense a parameter indicative of the force required to support material on the conveyer or the power used to load it into the truck. During operation, however, milled material and other debris can accumulate on and around the parts of a conveyor, which can reduce the accuracy of the measurement system over time.
One attempt to monitor the weight of material moved by a conveyor is disclosed in U.S. Pat. No. 7,193,162 that issued to McIsaac et al. on Mar. 20, 2007 (“the '162 patent”). In particular, the '162 patent discloses a system for measuring the weight of material moved by a conveyor based on the power consumed by an electric motor that drives the conveyor. The power consumed by the electric motor is measured with a watt transducer. A watt transducer reading is taken once per day when there is no material on the conveyor to determine a “no load” power consumption. Power consumed in excess of the “no load” power is correlated to the weight of material moved by the conveyor using a calibration relationship. The weight of material moved by the conveyor is tabulated over a period of time to determine a material production rate. Power consumed at or below the “no load” power is separately tabulated and not included in the weight determination. Surges in the power consumed by the electric motor that occur during the initial startup of the conveyor are also separately tabulated and excluded from the weight determination.
While the system of the '162 patent may determine the weight of material moved by a conveyor under some circumstances, it may not be optimum. In particular, the system of the '162 patent may produce inaccurate results when the actual “no load” value increases throughout the day. Further, if the “no load” power drops below the initial “no load” reading during that day, the weight of material needed to increase the load on the motor to the initial “no load” power may be erroneously omitted from the determination of material weight moved by the conveyor.
The yield measurement system of the present disclosure solves one or more of the problems set forth above and/or other problems in the art.